1. Field of the Invention
The present invention relates to automated systems and methods for performing vend operations on articles selected by a purchaser. More specifically, the present invention relates to such a system or method which utilizes a helical transfer member holding plural articles in a storage section and rotatable to dispense an article.
2. Description of Background Information
Vending machines hold articles to be purchased within sections of a helical member. When the helical member is rotated, it forwards the article to the entrance of a chute which leads to a catch bin accessible through a vend opening. U.S. Pat. No. 5,303,844 to Muehlberger (the '844 patent) discloses one example of such a system. In that patent, the vending machine has a rear vertical chute which curves gradually under trays holding articles to be dispensed and communicates with a vend opening. The system utilizes a dispense sensor positioned at the exit side of each tray, and the dispense sensor detects when an individual article passes into the chute. A helix is continuously turned until the article is dispensed into the chute as sensed by the dispense sensor. Another sensor is provided to detect whether an article is present at the discharge end of the helix.
There are problems associated with existing or conventional vending systems. For example, the '844 patent system allows its helix to rotate until a vend is sensed by the passage of the article across a beveled surface provided at the exit end of the tray. While doing this, the helix may rotate so far that the next article is susceptible to slipping past and over the beveled surface into the chute. If the next article does not fall into the chute due to its own weight, it may be dislodged by the unscrupulous passerby by simply jarring or rocking the machine.
Some vending machines provide ejectors on the end of each helix, which comprise small plastic projections that force the product off the shelf slightly sooner than if the helix had no ejector. This allows the rotation in the dispensing direction to be stopped sooner, thereby allowing the helix to maintain a better grip on the next article, holding the next article and preventing it from slipping off the shelf. Some existing vending machines utilize helixes with such ejectors, and vend articles by rotating the helix one complete revolution (i.e., 360 degrees) per dispensed article. With this solution, however, it is necessary to provide separate ejectors on the ejecting end of each and every helix, which can increase material and assembly costs.
There is a need for a vending system which is simple in construction, yet ensures both the dispensing of an article when properly paid for, as well as the retention and storage of articles not yet paid for.